Abstract
A good understanding of the physical and chemical properties of the surfaces of materials is required, to ensure that the correct combination of materials are joined, to form a strong and long term adhesive bond. For the purposes of both research and in-process quality control techniques, the surface free energy of a polymer can be determined from the contact angle measurement of a pure liquid drop on that polymer, and so in turn, understand the adhesion potential of that solid surface.
The thermodynamic principles are discussed in this review, and used to develop some mathematical descriptions of contact angle. Outlines of important experimental techniques, along with methods for interpreting data are given. One of the objectives of this paper is to give a clear understanding of the theory and practice of these methods, to demonstrate that they can be used readily as both research and quality control tools, and so can be employed more commonly by the polymer industry.
A number of case studies are described, in which the contact angle method has been used to investigate surfaces and effects of surface treatments. This includes studies of surface treated polyolefins to be printed or painted, and oxidised carbon fibres to enhance their reinforcing properties. This data is shown to have a good correlation with surface chemical analysis methods.
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